View Full Version : What are the mirror balls used for HDRI
02 February 2004, 08:34 AM
I have seen them used in "the making of...." on dvds. I know they capture light information but "exactly" are they used to duplicate lighting etc. Can anybody explain the process? Thanks!
02 February 2004, 08:38 AM
sorry, I got ther server busy message but I guess it went through...sorry for the double post!
02 February 2004, 09:48 AM
You use a mirrored ball to capture the lighting information in a wide field of view (around 270 degrees I think). That way you can use an unwrapped versoin of the map to make environment maps for reflecting a real environment in a CG object or to actually illuminate it using image based lighting techniques, You can make high dynamic range images if you wish that contain more lighting information if you like, but often it's not necessary. Some links for you:
www.debevec.org The daddy of all this kind of thing. He popularised and redefined HDRI.
www.rendermania Simon Bunker's site has some really good HDRI stuff on it.
www.andrew-whitehurst.net/hdri_tut.html my crappy tutorial on making and using HDRI maps.
That lot should answer any questions you might have.
02 February 2004, 10:49 AM
Hey Andrew, has very good style the work of your website, mainly the work for Hallmark :applause:
I take off my hat
02 February 2004, 03:10 AM
thanx for the information, pretty cool stuff. One thing I get very confused about and may sound dumb is...............how do you know which image to use in which situation and does every HDRI situation have to be produced with its own unique HDRI image? I've heard of people that swear on HDRI and will use nothing else, as I'm sure if i knew how to use it properly i would too.
"overthinking, overanylizing separates the mind from the body"
- Maynard James Keenan (lead singer from Tool)
02 February 2004, 02:27 AM
Sorry, I don't understand your question well, but if you have made the HDRI well (360 degrees and a wide exposure spectrum) and if the illumination conditions or the elements of the place don't vary drastically in oneself scene, you can use the same image with good results.
For example in Hulk there is a scene where he destroys a laboratory, because the conditions of illumination were very different when the scene begins and when it finish, the filmakers made two images HDRI to match both conditions of light.
"If you use HDRI then you don't use nothing else" it isnīt very certain; the HDRI are good to capture the global environmental illumination, but they have problems to simulate sources of hard light (as artificial light, for example) reason why if in a scene artificial light exists, is always good to make a note of the type of light, intensity, color temperature, distances, position, rotation, etc. to match them with the lights of the 3D software later.
03 March 2004, 01:50 PM
if you have a lot of money got to ->
it's make incredible result!!
03 March 2004, 03:58 AM
Hehe, yes , but you can achieve the same results with a little bit more work and much less money believe me.
03 March 2004, 08:15 AM
I'm working on a toolkit for doing this, you can see some results here (http://www.kidwars.com/demodvd.mov)
01 January 2006, 11:00 AM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.